It wasn't super hard but it was rather time consuming. Apart from a select few, the features individually were not very complicated to add. I gave myself a restriction of not adding any real extra assets just so the scope doesn't get out of hand for example. But since there are so many settings, they all took a long time to properly implement and test.

If you want to get into modding the PC port I'll say that some previous familiarity with C and C-like languages would really help if you want to add more than just maps and models. Once you know what you're doing, doing simple changes is not hard at all. Even adding new enemies and whatnot shouldn't be a super difficult side from a purely programming perspective.

That being said, difficulty is a relative thing. When I say it wasn't hard, I'm mostly comparing it to my other projects like Operius and Flashback. To someone who's not as experienced at programming, it might be a bit confusing or even intimidating.

As for updates, I'm planning to release an update to fix the remaining issues but I'm mostly done with it otherwise. I'm not adding any more new content, that's for sure.